Cleanup usage of history namespace in components/history

components/history/core/browser/visitsegment_database.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef COMPONENTS_HISTORY_CORE_BROWSER_VISITSEGMENT_DATABASE_H_
 #define COMPONENTS_HISTORY_CORE_BROWSER_VISITSEGMENT_DATABASE_H_
 
 #include "base/basictypes.h"
 #include "components/history/core/browser/history_types.h"
 
-class PageUsageData;
-
 namespace sql {
 class Connection;
 }
 
 namespace history {
 
+class PageUsageData;
+
 // Tracks pages used for the most visited view.
 class VisitSegmentDatabase {
  public:
   // Must call InitSegmentTables before using any other part of this class.
   VisitSegmentDatabase();
   virtual ~VisitSegmentDatabase();
 
   // Compute a segment name given a URL. The segment name is currently the
   // source url spec less some information such as query strings.
   static std::string ComputeSegmentName(const GURL& url);
@@ skipping 54 matching lines @@
   // presentation table is removed entirely.
   bool MigratePresentationIndex();
 
  private:
   DISALLOW_COPY_AND_ASSIGN(VisitSegmentDatabase);
 };
 
 }  // namespace history
 
 #endif  // COMPONENTS_HISTORY_CORE_BROWSER_VISITSEGMENT_DATABASE_H_